Electric motor-and-gear assembly for vehicle accessories

ABSTRACT

An electric motor-and-gear assembly for driving vehicle aggregates such as windshield and rear window wipers, power-window units and the like, having a transmission housing that can be closed by a housing cover. A motor housing that contains a commutator motor whose commutator protrudes into the transmission housing and cooperates with a brush holder fixed in the transmission housing. For the sake of a more reasonably priced manufacture and a time-saving, more rapid assembly of the brush holder, the commutator brushes are embodied as hammer brushes with spring leaf actuators prestressed toward the commutator. The spring leaf actuator are respectively fixed with their one actuator end in a U-shaped plastic carrying part of the brush holder, which is inserted into the transmission housing radial to the commutator, through the housing opening and is positioned in the transmission housing in a positively engaging manner by means of the housing cover.

PRIOR ART

The invention is based on an electric motor-and-gear assembly fordriving vehicle aggregates such as windshield and rear window wipers,power-window units and the like.

A known motor-and-gear assembly for power-window units in motor vehicles(DE 90 13 006 U1) has a transmission housing which adjoins thecommutator end of the commutator motor and into which the elongatedmotor shaft protrudes as a transmission drive shaft (worm shaft). Aprinted circuit board is disposed in an electronic housing and iselectrically connected to an external connector plug and commutatorbrushes as well as components of a set of motor electronics. The printedcircuit board has a one-piece receiving part for the brush holder and aone-piece receiving part for the connector plug. The electricalconnections of the components, the commutator brushes, and the connectorplug are contacted by the strip conductors of the printed circuit board.The commutator brushes are disposed diametrically opposed on thecommutator and are respectively held so that they can move radially in atubular brush holder embodied in the brush holder. The electronichousing is a component of the transmission housing and is closed by anelectronic housing cover that is of one piece with the transmissionhousing.

ADVANTAGES OF THE INVENTION

The electric motor-and-gear assembly according to the invention fordriving vehicle aggregates has the advantage that the embodiment of thebrush carrier as a U-shaped carrying piece on the one hand and theembodiment of the commutator brushes as so-called hammer brushes on theother hand assures an inexpensive manufacture of the brush holder and atime-saving, simple assembly since after the motor-and-gear assembly hasbeen completely assembled, the brush holder can be slid radially overthe commutator through the housing opening in the transmission housingin a single work cycle and is thereby positioned in the transmissionhousing in a highly precise manner. No other manipulations or adjustingmeasures are required. Since the hammer brushes are affixed to the brushholder, their sliding bodies, also called carbon strips, also rest in aprecise position on the circumference of the commutator after theinsertion of the brush holder. When the transmission is closed by meansof the transmission cover, the brush holder is securely fixed withoutadditional steps.

The hammer brushes have the advantage that the spring steel sheets havea very favorable ability to dissipate heat from the sliding bodies andtherefore the carrying part itself does not have to assume anyheat-dissipating function so that the carrying part can be inexpensivelymade of plastic. The manufacture of the carrying part of plastic makesit possible, through the injection molding of additional pockets ontothe carrying part, for components for the motor electronics, such asthermal circuit breakers, interference suppression elements (capacitor,throttle), to be inserted into the brush holder itself and thereforepermits a simplified assembly after a prior assembly of the brushholder.

Advantageous improvements and updates of the electric motor-and-gearassembly are possible by means of the measures set forth hereinafter.

According to a preferred embodiment of the invention, at least oneelastomer element is disposed between the underside of the carrying partoriented toward the transmission cover and the inside of thetransmission cover. This elastomer element is preferably part of a seal,which is injection molded onto the transmission cover and is made, forexample, of rubber-like material. These measures achieve an extensivedecoupling of the brush holder from the transmission cover, which isalso made of plastic, and thus achieves a noise reduction.

According to an advantageous embodiment of the invention, assembly aidsfor sliding the brush holder onto the commutator are embodied on thefree ends of the spring leaf actuators of the hammer brushes. Theseassembly aids, which are preferably embodied as projections withinsertion bevels and are inclined toward the outside from the end of thespring leaf actuators, make it significantly easier to slide the hammerbrushes onto the commutator and the assembly of the brush holder can beexecuted without auxiliary tools.

According to an advantageous embodiment of the invention, the pigtailsfor the hammer brushes are fixed in clamping forks embodied on thecarrying part, preferably of one piece with the carrying part. Thisachieves an assembly-facilitating fixing of the pigtails which isimperative for a noise reduction and increased service life of themotor.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be explained in detail in the description below inconjunction with an exemplary embodiment shown in the drawings.

FIG. 1 shows a longitudinal section through a motor-and gear assemblyfor a vehicle windshield wiper,

FIG. 2 shows a section through the empty transmission housing of themotor-and-gear assembly, along the line II—II in FIG. 1,

FIG. 3 shows a side view of a brush holder in the motor-and-gearassembly according to FIG. 1,

FIGS. 4 and 5 each show a depiction equivalent to the one in FIG. 3 ofthe brush holder according to two additional exemplary embodiments,

FIG. 6 illustrates a clip set forth in FIG. 3 which are shown on alarger scale, and

FIG. 7 illustrates the ends of a spring lever and a commutator on whicha wiper body rests.

DESCRIPTION OF THE EXEMPLARY EMBODIMENT

The electric motor-and-gear assembly depicted in the longitudinalsection in FIG. 1, which is for a windshield wiper in motor vehicles, asan exemplary embodiment for a general vehicle aggregate, has atransmission housing 10 and a motor housing 11 attached to thistransmission housing 10. The transmission housing 10, which contains atransmission not shown here, has a mounting opening 12 that is closed bya housing cover 13, with the interposition of a seal 40. A commutatormotor 14 with a stator 15 and rotor 16 is contained in the motor housing11. An elongated rotor shaft 17, supports the rotor 16, and protrudesinto the transmission housing 10 as a transmission drive shaft of thetransmission that carries a worm gear 18. The transmission drive shaftis supported so that the transmission draft shaft can rotate in a slidebearing 19 in the motor housing 11 and in a roller bearing 20 in thetransmission housing 10. A rotor winding 21 contained in the rotor 16 isconnected in an electrically conductive fashion to the commutatorlamellas of a commutator 22 connected to the rotor shaft 17 in anon-rotatable fashion. A brush holder 23 with three commutator brushes24 (FIG. 3) for the operation of the commutator motor 14 at twodifferent speeds is positioned and fixed in the transmission housing 10in a positively engaging manner.

As can be seen from FIG. 3, the brush holder 23, which can only be seenin a sectional view in FIG. 1, has a U-shaped carrying part 25 made ofplastic to which the three commutator brushes 24 are connected. Thethree commutator brushes are embodied as hammer brushes. Each hammerbrush 24 has a spring leaf actuator 26 that is prestressed toward thecommutator 22 and is fastened with one actuator end in the yoke 251 ofthe U-shaped carrying part 25 and at another actuator end, carries asliding body for the current consumption or current supply to or fromthe commutator 22, such as a carbon strip 27. The carbon strip 27, whichis pressed against the circumference of the commutator 22 by the springforce of the spring leaf actuator 26, is slid through a recess in thespring leaf actuator 26 from the back side of the spring leaf actuator26 oriented away from the commutator 22 and is prevented from movingaxially by means of a clip 28 embodied on the spring leaf actuator 26.FIG. 6 has been added to illustrate the clips 28 and carbon strip 27 inan enlarged view. Each carbon strip 27 is connected in a known fashionby means of a pigtail 29 to a connector plug not shown. The pigtail 29can either be sintered into the carbon strip 27 or can be bonded ontothe spring leaf actuator 26. In order to fix the pigtail 29, it isclamped in a clamping fork 30 that is injection molded onto the yoke 251of the U-shaped carrying part 25.

The fixing of the spring leaf actuators 26 in the carrying part 25 cantake place in different ways. In the exemplary embodiment of FIG. 3, thecarrying part 25 has a total of three slots 31 which are let into thecarrying part 25 from one side and predetermine the position of thespring leaf actuators 26 by means of their alignment in relation to theaxis of the brush holder 23. The three spring leaf actuators 26 arepressed with their one actuator end into the slots 31. For precisepositioning, the spring leaf actuators 26—as in the exemplary embodimentof FIG. 3—can also be provided with lugs 32 at one end to provide forprecise positioning of the spring leaf actuators 26 in the slots 31. Thespring leaf actuators 26 are prevented from sliding out of the slots 31by means of covering pieces, which are pressed into the slots 31 in apositively and frictionally engaging manner after the insertion of thespring leaf actuators 26.

In the exemplary embodiment of FIG. 4, the spring leaf actuators 26 areembodied as insert pieces that are molded-in at the ends when theplastic carrying part 25 is injection molded.

In the exemplary embodiment of FIG. 5, the actuator ends of the springleaf actuators 26 are angled and fastened to the inside of the yoke 25of the U-shaped carrying part 25. They can be fastened by means ofultrasonic welding, screw connection, or thermal caulking. In the lattercase, positioning pins 42 are embodied on the carrying part 25 and theangled actuator ends of the spring leaf actuators 26 are placed ontothese positioning pins 33 during the thermal caulking.

During the manufacture of the brush holder 23 according to FIG. 5, thespring leaf actuators 26 can be produced as individual parts and can beseparately connected to the carrying part 25. In terms of assembly, itis advantageous to manufacture the spring leaf actuators 26 out of asingle piece of spring steel sheet so that the spring leaf actuators areof one piece with one another and only after attachment to the carryingpart 25, to separate the spring leaf actuators 26 from one another forwhich purpose dividing points are already provided in the spring steelsheet.

In all of the brush holders 23 according to FIGS. 3 to 5, the springleaf actuators 26 of the two spring leaf actuators 26 are disposedopposite one another on the commutator 22 and have so-called assemblyaids 33 which make it easier to slide the hammer brushes 24 onto thecommutator 22 during assembly of the brush holder 23. These assemblyaids 33, which are only schematically depicted in FIGS. 3 to 5, arecomprised of clips 34 splayed outward from the end of the spring leafactuators 26 which slide against the commutator circumference duringassembly of the brush holder 23 and thus make it possible for thecommutator 22 to easily spread apart the two hammer brushes 24 disposedopposite each other.

In the two exemplary embodiments of the brush holder 23 according toFIGS. 3 and 4, an additional pocket 35 is injection molded onto thecarrying part 25, into which a thermal circuit breaker 36 is inserted,which is mounted on a grounding plate 361. It is possible to injectionmold additional pockets onto the carrying part 25 for containinginterference suppression elements (capacitor, throttle).

During the assembly of the motor-and-gear assembly, when themotor-and-gear assembly is end-mounted, the completed brush holder 23 isinserted into the transmission housing 10, radial to the rotor shaft 17,through the still-open housing opening 12 in the transmission housing10, wherein the two opposing commutator brushes 24 slide against thecommutator 22. In the end position of the brush holder 23, the carbonstrips 27 of the two opposing hammer brushes 24 rest in a preciseposition on the circumference of the commutator 22 and also, the carbonstrip 27 of the third hammer brush 24 is pressed in a precise positionagainst the commutator circumference as shown more clearly in FIG. 7.The precise positioning of the brush holder 23 in the transmissionhousing 10 is provided for by positioning faces 37, 38 (FIG. 2) embodiedin the transmission housing, which are adjoined in a positively engagingfashion by the front ends of the two arms 252 and 253 of the U-shapedcarrying part 25. The two positioning faces 37 provide for a positioningof the brush holder 23 in the y-direction and the two positioning faces38 provide for a positioning of the brush holder 23 in the x-directionof the y, x coordinate system shown in FIG. 2 so that the brush holder23 is fixed in relation to the commutator 22 in two radial directionsaligned at right angles to one another.

After the insertion of the brush holder 23 into the transmission housing10, the housing opening 12 is closed as a last step by the placement andscrewing of the housing cover 13. With an elastomer element 39 injectionmolded onto its inside pointing toward the interior of the housing, thehousing cover 13 presses against the yoke 251 of the carrying part 25and thus, together with the positioning faces 37, 38, fixes the brushholder 23 so that the brush holder cannot move in the transmissionhousing 10. This elastomer element 39 is part of a seal 40 that is madeof rubber-like material injection molded onto the inside of the housingcover 13 and seals the housing opening 12 between the transmissionhousing 10 and the housing cover 13 in a watertight and dust-tightmanner.

The foregoing relates to a preferred exemplary of embodiments of the A,invention, it being understood that other variants and embodimentsthereof are possible within the spirit and scope of the invention, thelatter being defined by the appended claims.

We claim:
 1. An electric motor-and-gear assembly for driving vehicleaggregates comprising a transmission housing (10) including a housingopening (12) that is closed by a housing cover (13) when assembled foroperation, a motor housing (11) attached to the transmission housing(10), a commutator motor (14) contained in the motor housing (11), saidcommutator motor includes an elongated rotor shaft (17), which rotorshaft has an axis and supports a commutator (22), wherein the elongatedrotor shaft protrudes into the transmission housing (10), a brush holder(23) fixed within the transmission housing (10), which brush holder (23)supports at least two commutator brushes (24) that rest against thecommutator (22) with a spring force, the brush holder (23) having aU-shaped carrying part (25), and the commutator brushes (24) eachincludes a spring leaf actuator (26) prestressed toward the commutator(22), each spring leaf actuator (26) including a first actuator end (43)and a second actuator end (44), wherein each first actuator end (43) isfixed to the carrying part (25), and each second actuator end (44)supports a sliding body (27) that rests against the commutator (22),each sliding body (27) being fixed to the second actuator end (44) andguided against the commutator (22) only by said second actuator end(44), wherein the brush holder (23) is inserted into the transmissionhousing (10) through the housing opening (12) radially to the commutator(22), and the transmission housing (10) having positioning faces (37,38) oriented at right angles to each other, and said positioning facesalso being oriented such as to face in directions which are radial tothe axis of the elongated rotor shaft, whereby the carrying part (25) ofthe brush holder (23) is positioned properly in radial directions atright angles to each other in relation to the commutator (22) by meansof the carrying part (25) engaging the positioning faces (37, 38). 2.The motor according to claim 1, wherein the carrying part (25) is fixedin the transmission housing (10) by means of the housing cover (13) thatis placed onto the housing opening (12) upon assembly.
 3. The motoraccording to claim 2, in which at least one elastomer element (39) isdisposed between one side of the carrying part (25) oriented toward thehousing cover (13) and an inside of the housing cover (13).
 4. The motoraccording to claim 3, in which the at least one elastomer element ispart of a seal (40) that is made of a flexible material and is injectionmolded onto the housing cover (13).
 5. The motor according to claim 1,in which in order to fix the spring leaf actuators (26) to the carryingpart (25), the carrying part (25) has slots (31) that feeds into oneend, into which the actuator ends (43, 44) of the spring leaf actuators(26) are slid in a clamping fashion.
 6. The motor according to claim 5,wherein the slots (31) in the carrying part (25) are aligned so thatafter their ends are slid into the respectively associated slot (31),the spring leaf actuators (26) are precisely positioned in relation tothe commutator (22).
 7. The motor according to claim 1, wherein thespring leaf actuators (26) are embodied as insert pieces that aremolded-in at the ends during the production of the carrying part (25),which is embodied as an injection-molded plastic part.
 8. The motoraccording to claim 1, wherein the actuator ends of the spring leafactuators (26) are angled and are fastened to an inside of the carryingpart (25) pointing toward a U-opening by a securing means.
 9. The motoraccording to claim 8, in which the spring leaf actuators (26) are of onepiece with one another and after attachment to the carrying part (25),are separated from one another, at prepared dividing points.
 10. Themotor according to claim 1, in which clips (28) are embodied on thespring leaf actuators (26) in order to fix sliding bodies (27) in apositively and frictionally engaging manner.
 11. The motor according toclaim 1, in which assembly aides (33) are embodied at free ends of thespring leaf actuators (26), and are of one piece with each spring leafactuator (26) to make it easier to slide the spring leaf actuators (26)onto the commutator (22).
 12. The motor according to claim 1, in whichpigtails (29) for the sliding bodies (27) are fixed in clamping forks(30) embodied on the carrying part (25) and are of one piece with thecarrying part.
 13. The motor according to claim 1, in which a thermalcircuit breaker (36) is clipped into the carrying part (25) and that thethermal circuit breaker (36) is affixed to a ground plate (361).